Compact fluorescent lamp products of the type having a lamp and integral ballast provide energy savings and have a longer useful life as compared to incandescent lamps of equivalent light outpul Typical compact fluorescent lamps have tubular envelopes with one or more generally U-shaped bends. The number of bends in the lamp is a function of the desired light output and size of the lamp. Compact fluorescent lamps may utilize electrodes or may be electrodeless. The lamp is connected to an electromagnetic or electronic ballast, the latter being preferred because electronic ballasts are more compact. In a typical compact fluorescent lamp system, the interface between the lamp and ballast is the widest physical dimension.
The overall length of a compact fluorescent lamp and ballast exceeds that of an equivalent incandescent lamp. The most common configuration of an incandescent lamp is referred to as A-line. There are three typical A-line bulb sizes, that is, A19, A21 and A23, with the number corresponding to the maximum diameter of the bulb in eighths of inches. For example, an A21 bulb is twenty-one eighths, or 25/8, inches in maximum diameter. Typical power outputs of such A-line incandescent lamps is in the range from about 25 to 250 Watts. Disadvantageously, presently available compact fluorescent lamps which use less energy and have a longer useful life cannot be used in incandescent lamp fixtures.
Accordingly, it is desirable to provide a compact fluorescent lamp capable of operating in incandescent lamp fixtures ,